Photography prices can vary greatly. Like PP said, it can be anywhere from $2000 to $7000. I'd recommend making a list of things you want in a photographer (i.e. one shooter or two, how many hours of coverage, rights to photos, engagement session, artistic style, etc) and then start researching photographers within your parameters to get a feel for their prices.

We went with Unique Concepts. He did our friends' wedding a couple years ago and is not super cheap, but he's very good at what he does. We're really happy with our engagement photos and he's super nice! We're paying about $3500 total. We were willing to pay a bit more for a photographer we knew we'd love.